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The present study investigates the mechanism by which lignin enhances the moisture resistance of asphalt materials, employing a combination of atomic force microscopy (AFM) and molecular simulations. The research aims to understand the changes in surface morphology and adhesion properties of asphalt upon immersion, and elucidate the role of lignin modification in mitigating the reduction of adhesive forces. AFM measurements reveal that lignin-modified asphalt exhibits higher adhesion force after moisture damage, possibly attributable to less nanostructures on the surface of lignin modified asphalt. Molecular dynamics simulations are employed to study the binding energies between lignin and different asphalt constituents. The results demonstrate that lignin exhibits the strongest binding affinity with asphaltene molecules, and also displays significant binding affinity with a specific saturated molecule. Furthermore, diffusion of water molecules on asphalt surfaces is investigated, revealing that lignin-modified asphalt exhibits lower water molecule diffusion coefficients and reduced binding energies. Finally, a spherical water molecule model is employed to analyze the wetting behavior on lignin-modified asphalt surfaces, illustrating the dual mechanism of lignin molecules resisting water molecules and inhibiting the binding of polar molecules within asphalt to water molecules. The findings of this research provide insights into the enhancement of moisture resistance in asphalt materials through lignin modification. The combination of AFM and molecular simulations offers a comprehensive understanding of the morphological and adhesive changes at the nanoscale, as well as the fundamental molecular interactions involved. The results contribute to the development of strategies for designing and engineering asphalt materials with improved resistance to moisture damage. [ABSTRACT FROM AUTHOR]

Potential damage, eventually demonstrated as moisture damage on inner and in-situ road structures, is the most complex problem to predict, which costs lots of money, time, and natural resources for maintenance and even leads to safety problems. Traditional linear regression analysis cannot fit well with this multi-factor task in such in-field circumstances. Random Forest (RF) is a progressive nonlinear algorithm, which can combine all relative factors to gain accurate prediction and good explanation. In this study, an RF model is constructed for the prediction of potential damage. In addition, relative variable importance is analyzed to obtain the correlations between factors and potential damage separately. The results show that, through the optimization, the model achieved a good average accuracy of 83.33%. Finally, the controlling method for moisture damage is provided by combining the traditional analysis method and the RF model. In a word, RF is a prospective method in predictions and data mining for highway engineering. Trained with effective data, it can be multifunctional and powerful to solve hard problems.

Recently, damage to asphalt pavements in South Korea has increased because of direct and indirect factors caused by abnormal climatic changes, such as torrential rains, prolonged heatwaves in summer, and heavy snowfall in winter. Additionally, the use of medium and heavy vehicles is also a contributing factor. Therefore, an experimental procedure to study the moisture damage and fracture properties of asphalt pavements considering the recent changes in precipitation properties, deterioration of road pavement, and traffic conditions in South Korea was developed in this study. Additionally, changes in material properties according to the indoor aging process and fatigue crack resistance were evaluated for hot mix and warm mix asphalt mixtures of the same grade and different initial production and construction temperatures. To evaluate the effect of aging and moisture damage on fatigue cracking, the experimental coefficient values of the predictive model were calculated for each condition. It was observed that the material properties of hot mix asphalt mixtures changed with an increase in aging and moisture damage. The service life of the pavement was reduced by approximately 40–80% owing to moisture damage, whereas aging had a greater effect on fatigue life as the service life increased.

Abstract Background The limited understanding of microbial characteristics in moisture-damaged buildings impedes efforts to clarify which adverse health effects in the occupants are associated with the damage and to develop effective building intervention strategies. The objectives of this current study were (i) to characterize fungal and bacterial microbiota in house dust of severely moisture-damaged residences, (ii) to identify microbial taxa associated with moisture damage renovations, and (iii) to test whether the associations between the identified taxa and moisture damage are replicable in another cohort of homes. We applied bacterial 16S rRNA gene and fungal ITS amplicon sequencing complemented with quantitative PCR and chemical-analytical approaches to samples of house dust, and also performed traditional cultivation of bacteria and fungi from building material samples. Results Active microbial growth on building materials had significant though small influence on the house dust bacterial and fungal communities. Moisture damage interventions—including actual renovation of damaged homes and cases where families moved to another home—had only a subtle effect on bacterial community structure, seen as shifts in abundance weighted bacterial profiles after intervention. While bacterial and fungal species richness were reduced in homes that were renovated, they were not reduced for families that moved houses. Using different discriminant analysis tools, we were able identify taxa that were significantly reduced in relative abundance during renovation of moisture damage. For bacteria, the majority of candidates belonged to different families within the Actinomycetales order. Results for fungi were overall less consistent. A replication study in approximately 400 homes highlighted some of the identified taxa, confirming associations with observations of moisture damage and mold. Conclusions The present study is one of the first studies to analyze changes in microbiota due to moisture damage interventions using high-throughput sequencing. Our results suggest that effects of moisture damage and moisture damage interventions may appear as changes in the abundance of individual, less common, and especially bacterial taxa, rather than in overall community structure.

Using nano-technology materials in the asphalt pavement industry is new compared with Portland cement concrete. The main objective of this study is to investigate the effects of nano-silica modification on some properties of a penetration grade asphalt cement and a typical asphalt concrete. 60/70 penetration grade bitumen was modified with different percentages of nano-silica (i.e. 1, 3 and 5%, by weight) and was used for making the asphalt concrete specimens. After evaluating the basic properties of the modified binder, the asphalt concrete specimens were evaluated based on the stiffness and resistance against fatigue cracking, moisture damage and permanent deformation. The fatigue life of the modified mixtures was also calculated using an already developed regression model. The results showed that penetration grade and ductility increase and softening point decreases with increasing nano-silica content. Furthermore, results showed that the addition of nano-silica results in the increase of stiffness, tensile strength, resilient modulus, fatigue life and resistance against permanent deformation and moisture damage. The reduction of indirect tensile strength in wet the condition decreases with increasing nano-silica content. Dynamic creep test results showed that, the flow number of the control mixture and the mixture containing 1% of nano-silica is much lower than 10000 loading cycles. However, the mixtures containing 3 and 5% of nano-silica do not reach to the tertiary creep region after 10000 loading cycles.

The study concentrated on the extent of moisture and mould damage in different structures in 25 public buildings in Finland. Users of all the buildings had health symptoms suspected to be the result of moisture and mould damage, which is why moisture performance assessments had been performed. The assessment reports on each building were available as research material. The reports indicated that the examined buildings suffered from multiple moisture and mould problems in several different structures. On average, however, a relatively small proportion of the total number of structures had suffered damage. On the basis of the research material, damage was most extensive in walls in soil contact (16.3%) and base floor structures (12.5%). The lowest damage rates were found in partition walls (2.4%), external walls (2.6%) and intermediate floors (2.5%). The results of the study underline the importance of thorough moisture performance assessments to ensure that all point-sized moisture and mould damage is detected.

Due to the significant methodological problems in the empirical part of the paper and the very selective literature review, the conclusions of the paper are mostly unsupported.

Indoor exposure to microbial growth, caused by moisture damage, has been an established health risk for several decades. It is likely that a damp indoor environment contains biological pollutants that trigger both the innate and adaptive branches of the immune system. In this study, we investigated the association between moisture damage related microbial exposure and serum C3a, C5a and CRP concentrations in Finnish adults. Serum C3a and CRP concentrations were elevated in individuals exposed to moisture damage and microbial growth in an indoor air environment. The elevated concentrations may be due to environmental factors present in moisture-damaged buildings. Complement activation and the resulting proinflammatory cleavage products may be a driving factor in inflammatory responses following exposure to indoor moisture damage and related microbial growth., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

This paper investigates the effects of Acrylonitrile Butadiene Styrene (ABS) polymer as an asphalt binder modifier on reducing the moisture susceptibility of hot asphalt mixtures. In order to recognise the efficiency of ABS polymer, repeated load tests in dry and wet conditions along with the thermodynamic parameters calculated through measuring the surface free energy (SFE) components of asphalt binders and aggregates were used. The results showed that ABS polymer caused an increase in the cohesion free energy and a reduction in the released energy of the system during stripping, indicating the reduced tendency of the system toward stripping. The results of repeated load tests supported the results obtained from the SFE method, demonstrating an improvement in moisture susceptibility of modified mixtures, especially the samples constructed by acidic aggregates. In addition, moisture sensitivity index was calculated using the thermodynamic parameters and asphalt mixtures modulus from cyclic loading tests. The results were similar to those of wet-to-dry modulus ratio and showed that ABS significantly reduced the stripping percentage of modified mixtures. [ABSTRACT FROM AUTHOR]

The Poisson's ratio (PR) of asphalt mixtures is an important input parameter in the constitutive models for pavement design and performance analysis. The design and performance analysis of asphalt pavements depend upon measuring proper material properties such as complex modulus and PR. The PR is often assumed to be time independent or it is calculated as the negative ratio of transverse to axial strains in the time domain under uniaxial loading when the time dependency is considered. This study used accurate methods to calculate the viscoelastic Poisson's Ratio (VPR) under various loading conditions and demonstrated the error associated with using inaccurate methods for calculating the PR. The results demonstrated that the VPR increased with time in uniaxial unconfined tension and compression tests where shear relaxation was generally faster than dilatational relaxation. While the VPR slightly decreased with time in uniaxial confined compression tests where the dilatational relaxation was faster than the shear relaxation. In addition, the results demonstrated that asphalt mixtures with coarse aggregate gradations had lower VPR compared to asphalt mixtures with finer aggregate gradations. Also, the VPR was found to be sensitive to the ageing and moisture conditions. The VPR decreased with ageing and increased with the level and time of moisture conditioning of the asphalt mixtures. Finally, the error introduced by incorrectly calculating the PR as the negative ratio of transverse to axial strains in the time domain was found to be significant in some cases, while it was insignificant in others. [ABSTRACT FROM AUTHOR]

This research focused the impact of various aggregate gradations on permanent deformation and moisture susceptibility of asphalt concrete mixtures. Five wearing course of different gradation, namely NHA-A, NHA-B, SP-1, SP-2 and MS-2, were adopted. Two paving grade bitumen i.e. 40/50 and 60/70 were used. Hamburg Wheel Tracking Test (HWTT) and Modified Lottman test were performed to assess rutting propensity and moisture damage of asphalt mixtures. The results indicated the superior performance of NRL 40/50 binder in HWTT while mixes prepared with Parco 60/70 showed better resistance against moisture. In HWTT, NHA-A performed well followed by NHAB and SP-2 while MS-2 and SP-1 failed the minimum rut depth criteria. All the mixtures passed the minimum benchmark for Tensile Strength Ratio (TSR). Aggregate gradation SP-1 given in Superpave guidelines provided greater resistance to moisture damage due to compact nature of the blend. Rutting tendency of the mixtures increased with increasing TSR and decreasing Indirect Tensile Strength (ITS). [ABSTRACT FROM AUTHOR]

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• We assessed the influence of the chemical composition of aggregates on moisture damage in HMA. • Three lithologies with an ample mineralogical and chemical spectrum were selected. • Asphalt-aggregate samples were tested in dry and in three moisture-related conditions. • Results show that mafic rocks were more resistant to moisture damage than felsic rocks. • Al 2 O 3 , Fe 2 O 3 , MnO, MgO oxides in rocks prevent moisture damage while SiO 2 promotes this phenomenom. Rock mineralogy is critical in determining the adhesion quality and moisture susceptibility of asphalt-aggregate systems in asphalt mixtures. This work aims at identifying the chemical properties of aggregates that influence the quality and durability of these systems. To accomplish this goal, three lithologies with an ample mineralogical and chemical spectrum (i.e. quartzite, granodiorite and serpentinite) were selected. Asphalt-aggregate specimens fabricated with these lithologies were tested using a new pull-off experiment in dry condition, and after 1, 3 and 7 days of being submerged in water. The results show that rocks of mafic composition (e.g. serpentinite) have better resistance to moisture damage than felsic rocks (e.g. quartzite and granodiorite), and that certain specific aggregate oxides promote or prevent moisture degradation in these systems. [ABSTRACT FROM AUTHOR]

• Aggregate source proved to be relevant for stripping and for moisture-induced damage. • Mixtures with the same base bitumen had stiffnesses differing in asymptotic elastic moduli. • Anti-stripping agent increased fatigue life of the investigated asphalt mixtures. • HMA with better aggregate-binder adhesiveness have shown longer fatigue life. • Adhesiveness seems to delay of microcraks when strain amplitudes are small. This study investigated the effects of aggregate-binder adhesiveness on moisture damage and on fatigue life of four different asphalt mixtures. Adhesivemeness was assessed by: (i) qualitative observation of binder stripping from the coarse aggregate's surface, incremented in this paper with digital image processing, and (ii) modified Lottman test. Fatigue damage modeling was performed, using tension-compression test results. The granitic aggregate produced mixtures with better moisture resistance and fatigue properties when compared to the phonolitic aggregate (same ranking as for aggregate-binder adhesiveness). The same was observed for mixtures with binder containing an anti-stripping agent. It was demonstrated that mixtures with better aggregate-binder adhesiveness have greater fatigue life. [ABSTRACT FROM AUTHOR]

Embankment dams with asphalt concrete cores have been constructed on practically all continents with satisfactory results. Nowadays many advantages, such as the mechanical strength, are known that makes asphalt concrete a competitive alternative for the construction of the impervious elements of dams. However, the current available information does not describe the effect of prolonged contact between asphalt concrete and water on the structure of an embankment dam. In this research cylindrical asphalt concrete specimens with a void content similar to that used in impervious barriers of dams were fabricated and submerged in water for a prolonged period to simulate the conditions experienced by asphalt concrete placed inside an embankment dam as its core material. Subsequently, triaxial compression tests were conducted on the specimens. The results indicated that the asphalt concrete exhibited a reduction in strength because of the saturation process to which the material was subjected. However, no changes were observed in the mechanical response to prolonged contact with water for periods of up to 12 months. [ABSTRACT FROM AUTHOR]

• The stiffness of asphalt concrete, after the saturation, remained constant. • No change was recorded in the dynamic response after 12 months of saturation. • Saturation cases an average decrease of 6.5% in the maximum shear modulus. • Saturation cases an average increase of 16.1% in the minimum damping ratio. Dams with an asphalt concrete core are a viable alternative in the construction of rockfill dams; therefore, characterization of the materials used in their construction is required. Part of this characterization requires obtaining the response parameters upon applying cyclic loads under different stress and temperature conditions. The objective of this research is to determine the effect of water on the dynamic properties of asphalt concrete after prolonged contact. To this end, an extensive program of laboratory tests was carried out in which specimens of this material were prepared, saturated and exposed to water. After the saturation process, the results of the tests indicated that the asphalt concrete presented a decrease in the shear modulus of 6.5% and an increase in the damping ratio of 16.1%, on average, with respect to the values obtained for the dry material. No significant change in the mechanical response was observed as a result of exposure to water for a period of up to 12 months. [ABSTRACT FROM AUTHOR]

• WMA produced at lower temperatures than HMA exhibited enhanced workability. • Specimens subjected to simultaneous LTA and water damage recorded the highest percentage adhesive failure and lowest ITS. • Polymer modified binder mixtures demonstrated superior moisture damage resistance than unmodified binder mixtures, regardless of conditioning method. The destructive effects of moisture remain to be the main distress adversely influencing pavement performance. Warm mix asphalt (WMA) compacted at lower temperatures than Hot Mix Asphalt (HMA) is more vulnerable to moisture infiltration and subsequent stripping at the asphalt-aggregate interface. To evaluate the potential mechanisms, the failure severity was computed in indirect tension. Two binder types and various compaction temperatures were used for sample fabrications. The gyratory compaction data were used to quantify the mixtures Workability Index (WI) and Compaction Energy Index (CEI). Six long-term conditioning methods were used namely, Long-Term Aged (LTA), Long-Term Aged + 1 Freeze-Thaw (F-T), LTA + 3 F-T, LTA + 1 F-T (Accelerated Laboratory Vacuum Saturation (ALVS)), simultaneous LTA + Moisture-Induced Damage and simultaneous LTA + Water Damage. The ALVS was used to subject asphalt mixtures to the combined effects of pore pressure and high temperature. As aging and moisture damage occur concurrently during the pavement service life, a new moisture conditioning chamber was fabricated to simulate the simultaneous effects of LTA and moisture/water damage. The effects of conditioning on the indirect tensile strength (ITS), fracture energy, resilient modulus and percentage adhesive failure were investigated. The percentage adhesive failure and broken aggregates were quantified using the advanced 3-D imaging technique. WMA compacted at lower temperatures exhibited improved workability in terms of lower CEI and higher WI than HMA. The mixtures percentage adhesive failure increased, while ITS reduced with F-T cycles. Asphalt mixtures subjected to simultaneous LTA and water damage exhibited the highest percentage adhesive failure and lowest ITS compared to other conditioning methods. ALVS conditioned specimens showed slightly higher percentage adhesive failure than LTA + 1 F-T specimens. The test results also demonstrated that polymer modified binder mixtures exhibited superior moisture resistance than unmodified binder mixtures, regardless of compaction temperature and conditioning level. [ABSTRACT FROM AUTHOR]

• New test for bond strength of bitumen and mastics. • This compression approach is useful than direct tension test. • A new gap assembly is developed for film thickness of binder. • CPOT is successful in evaluation of relevant testing parameters. The quantification of moisture susceptibility has been a major concern for researchers as it adversely affects the performance of asphalt pavements. Several methods have been developed to assess bond strength using asphalt mixtures in loose and compacted state. These tests lack in their ability to study fundamental properties that affect the bond between bitumen and aggregate. In this context, more fundamental techniques have been developed such as pull-off stub tests and direct tension tests. The first group only measures the maximum pull-off strength and second group has problems related to use of consistent binder film thickness and operational difficulties in test itself. This paper presents a new test to evaluate bond strength, in an attempt, to solve problems associated with traditional direct tension tests. The aim is achieved through a review of existing techniques, development of a gap assembly, fabrication of direct tension test moulds, development of Compression Pull-Off Test (CPOT) and evaluation of its results. The key parameters for bitumen and mastics were evaluated. The CPOT shows promising results for use of this technique to study cohesive as well as adhesive bond strength of binder. [ABSTRACT FROM AUTHOR]

One of the premature damages in asphalt pavements is moisture induced damage especially in the regions with high annual precipitation rate. The implementation problems of using the common additives in projects have led us to investigate the effects of using two types of liquid anti-stripping additives. Amongst the materials used in this research are two different types of aggregate with different moisture sensitivity potentials (limestone and granite), bitumen with the penetration rate of 60-70, and those two types of additives in different percentages. In order to investigate the effect of using additives, AASHTO T283 method in 1, 3, and 5 freeze-thaw cycles has been used to determine moisture sensitivity in hot mix asphalt. Moreover, to ensure that these materials do not negatively affect the other characteristics of mix asphalt, performance tests, including fatigue and rutting were conducted on the samples made using these additives. Results of this study show that using liquid anti-stripping additives causes a reduction in the moisture damage potential of asphalt mixtures. The positive effect of these additives has been more evident with greater numbers of freeze-thaw cycles. In addition, results of performance test show that the liquid anti-stripping additives have no negative effect on other characteristics of mix asphalt, including rutting and fatigue cracking. The influence of using these materials on increasing the fatigue life of the samples containing both types of aggregates used in this research has been evident. [ABSTRACT FROM AUTHOR]

Highlights • Moisture damage induced by dynamic pore water pressure exhibits a totally different failure mechanism. • Newly proposed dynamic pore water pressure conditioning methods and their applications are reviewed. • Relevant investigations on multiscale numerical simulation and field tests are analyzed. • Challenges on current research and future works are discussed. Abstract Under repeated vehicle loadings, surface runoff and retained water inside asphalt pavement structure will cause dynamic pore water pressure with positive and negative alternations. Such dynamic pore water pressure squeezes and pumps water flow along the inner wall of void channels to strip asphalt film and finally develop into moisture damage. Different from the traditional freeze-thaw and static water immersion mechanisms, dynamic hydraulic scouring induced by vehicle tires demonstrates a more general moisture damage of asphalt pavement in warm seasons or warm regions. This paper reviews extensive research works in the last decade about moisture damage of asphalt pavement induced by dynamic pore water pressure. A field survey of distresses characterization for an asphalt pavement is firstly introduced and analyzed. On the basis of analyzing macro-scale and micro-scale mechanisms of hydraulic scouring, traditional experimental methods for moisture damage evaluation are then discussed. Newly proposed three types of dynamic pore water pressure conditioning systems with their applications, which include pneumatic, piston and other types, are categorized and analyzed. Multiscale experimental investigations considering dynamic pore water pressure are discussed in detail. Numerical simulation on the water-mechanic response, moisture damage characteristics of asphalt pavement and the real-time monitoring of dynamic pore water pressure in field tests are also summarized. Finally, a series of measures to mitigate moisture damage from the perspective of dynamic hydraulic scouring is proposed. [ABSTRACT FROM AUTHOR]

Moisture damage reduces the mechanical properties of asphalt mixture via two main mechanisms (cohesion and adhesion failures). Accordingly, attempts were made in this research to investigate the effect of different mastic properties on parameters affecting adhesive failure mechanism. Two types of aggregate (limestone and granite) and four types of filler (stone powder, Portland cement, calcium carbonate and hydrated lime) were evaluated, in addition to AC 60/70 and 85/100 as asphalt binders. Results obtained in this research show that stone powder and Portland cement fillers increase acid components of binder, but calcium carbonate and hydrated lime fillers show a different behavior (reducing acid components in binder 60/70 and increasing acid property in binder 85/100). In addition, the use of binder causes a reduction in non-polar component. Results obtained by statistical analysis show that changing mastic type changes free energy of adhesion, but stripping parameter will not change significantly. [ABSTRACT FROM AUTHOR]

• A new concept of plastic materials in the hot mix asphalt. • Water saturation was considered during the design of new plastic mixtures. • Use of recycled polymers allow less rutting. • The mixing process of polymers influences the behaviour of the mixture over time. In recent decades, the generation of plastic waste has increased substantially worldwide, with the result that more of such waste is introduced into the environment. Currently, most polymers (polyethylene terephthalate, polyethylene, polyvinyl chloride, and others) are recycled. However, some are rejected for recycling in the primary separation processes due to their physical condition, contamination, or size. These materials are called plastic scrap. In this research, the use of plastic scrap added by dry method was evaluated as a replacement for bitumen in asphalt mixtures. Two sizes of plastic scrap, coarse and fine, were considered. An AC16S semi-dense mixture was designed for this purpose, with a 10% reduction in binder, and 10% and 20% of plastic scrap binder was added in coarse and fine sizes. The results obtained in the Marshall stability and flow test showed reduced moisture damage, greater indirect tensile strength, higher air void content, and a 2% decrease in the conserved tensile strength ratio while the same usage field as the conventional mixture was maintained. Meanwhile, significant decreases in plastic deformations, as compared to traditional values, were obtained from resilient modulus and rutting tests. [ABSTRACT FROM AUTHOR]

To date, most of the studies to evaluate moisture susceptibility of hot mix asphalt have been carried out by quantifying the degradation of the mix properties due to conditioning that simulates the action of moisture in the field. There is a need for research on the identi fication of moisture susceptible mixes which show the material loss in the wheel-path under the combined action of traffic and moisture. The objective of this study was to simulate and analyze the moisture induced material loss, and also to identify a mix with the potential of moisture induced material loss that has shown damage in the field but not under regular testing in the laboratory. The Moisture Induced Stress Tester (MIST), Ultrasonic Pulse Velocity (UPV), Dynamic Modulus in Indirect tensile mode, Indirect Tensile Strength (ITS), and Model Mobile Load Simulator (MMLS3) tests were utilized in the study. The effluent from the MIST was checked for the gradation of dislodged aggregates and the Dissolved Organic Carbon content. The results from the effluent ana lysis showed the loss of material and aggregate breakage from a moisture susceptible mix. A similar type of losses from the mix was also evident from MMLS3 loading under wethot conditions. The results of the mix mechanical properties showed that the use of MIST in combination with UPV or ITS is ab le to identify moisture susceptible mixes, in particular for mixes with the potential of aggregate breakage. [ABSTRACT FROM AUTHOR]

The adhesion between aggregate and asphalt binder in dry conditions, and the amount of its reduction in wet conditions are amongst fundamental indicators that moisture sensitivity amount of asphalt mixtures is dependent to. Among different methods to increase adhesion, modification of aggregates surface with anti-stripping materials is known as an effective method. Therefore, the effect of covering aggregates surface with micronized calcium carbonate as a proper and inexpensive anti-stripping material was investigated. Accordingly, in order to evaluate mixes, first, mechanical methods were used, and then thermodynamic methods were employed to determine the mechanism of the effect of calcium carbonate on increasing asphalt mix resistance to moisture damage. In order to conduct this research, three types of aggregates including limestone, granite, and quartzite, for their different degrees of hydrophilic, and two types of asphalt binder 60-70 and 85-100 were used to produce mixtures. Results obtained by mechanical methods show that modification of aggregates surface causes an increase in the tensile strength ratio (TSR) in the samples made by both two types of asphalt binder. In addition, results of surface free energy method indicate the increase of adhesion energy (except in granite samples) and reduction of debonding energy in all modified samples. Generally, evaluations conducted by the use of both methods show that covering aggregates by micronized calcium carbonate has a positive effect on reducing moisture sensitivity of asphalt mixes. [ABSTRACT FROM AUTHOR]

• Alternatives to AASHTO T283 for assessing moisture damage in asphalt mixtures were explored. • Correlations between Surface Free Energy (SFE) and Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) tests with AASHTO T283′s Tensile Strength Ratio (TSR%) were discussed. • The statistical significance of SFE and FTIR-ATR variables in differentiating asphalt binder types and oxidative conditioning levels was assessed. Moisture damage often leads to pavement failure, particularly as pavements age. The widely adopted AASHTO T283 test evaluates asphalt mixtures' susceptibility to moisture damage but has shortcomings, time-consuming procedures, and lack of representation of realistic aging effects. Given the adoption of AASHTO T283 by state agencies, this study aimed to establish correlations with reliable and practical tests, especially Surface Free Energy (SFE)'s work of cohesion (Wc) and Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) tests' carbonyl and sulfoxide indices, to estimate AASHTO T283′s Tensile Strength Ratio (TSR%). Three asphalt binders (PG 52–34, PG 64–22, and PG 76–22) were assessed at oxidation levels (original, short-term, and long-term). Analysis of Variance (ANOVA) and linear regression analysis were conducted to assess the relationship between SFE and FTIR-ATR with TSR%. Results showed PG 52–34 mixtures had the highest TSR%, while PG 76–22 mixtures had the lowest, decreasing with higher oxidation. PG 52–34 had higher Wc values than PG 76–22, reducing with higher oxidation. FTIR-ATR measured higher carbonyl and sulfoxide index values for PG 52–34 and lower values for PG 76–22. ANOVA and linear regression analysis highlighted correlations between TSR%, SFE, and FTIR-ATR, with the combined effects of Wc, carbonyl, and sulfoxide indices showing the strongest relationship. The findings demonstrate that SFE and FTIR-ATR measurements showed potential in predicted TSR% for the asphalt mixtures. Particularly, predicted TSR% values differed the highest from actual TSR% for PG 52–34 without aging and at short-term aging but achieved accurate predictions with small absolute differences under long-term aging conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of acid rain on the adhesion properties of the asphalt-aggregate interface was studied. • The effect of acidic ions on the movement of asphalt molecules was investigated. • The tensile separation process of asphalt-aggregate model under acidic environment was simulated. To further reveal the effect of acid rain on the interfacial adhesion of asphalt mixtures, molecular dynamics (MD) simulation was used to investigate the interfacial damage mechanism. A water layer containing hydrogen ions, sulfate ions, and nitrate ions was inserted between the asphalt and aggregate to simulate the effect of acid rain attack on the interface. The interfacial bonding strength under three conditions of dry, pure and acidic water was analyzed. The effect of acidic ions on the spatial arrangement and movement of asphalt molecules was discussed. The damage of the asphalt-aggregate interface under both pure water and acidic water attack was investigated. The results showed that the acidic ions promote the rearrangement distribution of asphalt molecules at the interface, reduce the concentration of asphalt molecules at the interface, and weaken the adhesion ability at the interface. The degree of aggregation of polar components increases, resulting in a reduction in the movement migration capacity of asphalt and poor mobility, increasing the possibility of asphalt stripping from the aggregate surface. Under the influence of acidic ions, less separation energy is required for interfacial adhesion damage to occur between asphalt and aggregate, and the amount of deformation at interfacial failure is smaller. [ABSTRACT FROM AUTHOR]

Moisture damage is one of the most frequent damages that occurs on asphalt pavements. The application of rubberized materials for asphalt is widely acceptable due to cost saving and environmentally friendly. The purpose of this study is to assess the performance of rubberized asphalt mixtures containing wax-based admixture, namely Tough Fix Hyper (TFH), in terms of moisture sensitivity and hazardous compound leaching potential. The moisture absorption, chemical immersion, and boiling water tests were used to assess the resistance to moisture damage on aggregate-binder bonding characteristics. Following that, the trend of moisture sensitivity was evaluated through an image analysis procedure. To simulate the environmental impact of leaching, the toxicity characterization leaching procedure (TCLP) test was adopted. The results showed that interaction between the crumb rubber or latex with TFH decreases the stripping value of the mixes significantly based on the chemical immersion test. Furthermore, the image analysis of the samples subjected to boiling water conditioning showed that pixels of asphalt samples without TFH, ranging from 524,949 to 472,346, decrease from 520,870 to 289,070, indicating that the asphalt remained coated area improved by 67.70–91.39%. The analysis of the leachate test revealed that the heavy metals, including arsenic (As), nickel (Ni), copper (Cu), chromium (Cr), vanadium (V), and cadmium (Cd), were not detected. However, zinc (Zn) was detected in the modified mixture, ranging from 0.05 to 0.114 mg/L, which lies within the allowable norm. In conclusion, the incorporation of crumb rubber and TFH in asphalt mixtures poses no environmental risk. • The performance of rubberized asphalt mixtures containing wax-based admixture was studied. • The moisture sensitivity was evaluated through an image analysis procedure. • The environmental impact of leaching was evaluated using TCLP test. • Samples subjected to boiling water indicated that the asphalt remained coated area improved within 68–92%. • The outcomes of the leachate test revealed that the incorporation of crumb rubber and wax admixture has no environmental risk. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel molecular modeling approach is developed to study nanoscale moisture damage. • Non-uniform diffusion of interfacial moisture is discovered for the first time. • The efficiency of interfacial moisture migration depends on the aggregate surface. • Calcite exhibits stronger hydrogen-bonding interactions with interfacial moisture. The asphalt-aggregate debonding behavior in moisture environments is a fundamental but unresolved issue in pavement engineering. In this study, a novel molecular dynamics (MD) modeling method was developed to address this challenge. Compared with previous layered modeling methods, the new method considers the moisture diffusion and migration at the interface, which better reflects the real debonding process. Based on the results, we found a layered diffusion phenomenon at the interface, which significantly affects the efficiency of moisture migration and interfacial debonding. The strong interactions between water molecules and alkaline aggregates (represented by calcite) restrict the interfacial moisture diffusion and migration, making it more resistant to moisture damage than acidic aggregates (represented by quartz). This study highlights the limitations of energy-based parameters obtained from the layered modeling method and resolves a long-standing controversy over whether calcite or quartz is more susceptible to water damage. Findings from this research contribute to comprehending the fundamental debonding mechanisms and provide an atomic-level perspective to investigate moisture damage in pavement engineering. [ABSTRACT FROM AUTHOR]

• The adhesion failure occurs earlier than that of cohesive failure caused by solution, which has been verified at the atomic scale. • The moisture sensitivity of mastic with different filler/binder ratio of interface has the respective characteristic. • Alkali solution deteriorates the most towards bitumen, bitumen-base and bitumen-aggregate interfaces. In order to analyze the decay process of fractions of asphalt mixture caused by solution erosion, molecular dynamics (MD) simulations and dynamic shear rheometer (DSR) tests were conducted to study the solution-induced response. The settled environments are salt, pure water, and alkali solutions, respectively. The cohesive failure of asphalt-solution-asphalt (A system), adhesive failure of asphalt-solution-quartz/calcite aggregate (B-1 and B-2 systems), and "water-aging" of bitumen and mastic were thereby concluded. Results show that the asphalt-base system has less susceptibility towards solution as compared to aggregate-base system, where the calcite-base one possesses the lowest energy ratio (ER) value, namely the least moisture resistance. Thus, adhesion failure of alkaline aggregate usually occurs first, while cohesive bonding in asphalt is considerably stable. Besides, the diffusion coefficient (D) value of SARA in asphalt-aggregate keeps higher than that in asphalt-base system, where water molecules have a stronger intervention effect. By constructing the master curves of complex shear modules (G*) via laboratory DSR results, it is verified that with the increase of erosion days, solution has "water aging" effect on virgin and SBS asphalt/mastic, and alkali solution performs the most deterioration. Here, mastic with 1.2 filler/bitumen ratio (FBR) maintains the most stable solution erosion resistance. [ABSTRACT FROM AUTHOR]

Moisture is one of the critical failures affecting asphalt pavement. It has been recently found that moisture created by rainwater and undrained water deteriorate the bonding interface between asphalt mastic and aggregate. Using different mineral fillers can lead to different moisture resistance in the same mix design. Nowadays, waste natural materials allow agriculturists to receive more income by recycling in many industries. In this study, the researchers adopted bagasse and coconut peat grinding into very fine particle passing through the sieve number 200 (0.075 mm) to replace the mineral fillers. Although the indirect tensile strength (ITS) test is commonly used for evaluating the moisture damage resistance of hot-mix asphalt (HMA) in a laboratory, there are some shortcomings in using this test, such as costly, heavy and indirect equipment. Another potential test that is likely to be more advantageous than the ITS test for evaluating the moisture damage resistance is the pull-off tensile strength (POTS) test. However, it is typically measured on a concrete surface, and no results using an asphalt mixture have been reported. The objectives in this study were to investigate the effects of waste natural fillers in asphalt mixture on adhesive bonding caused by moisture, and to determine whether the POTS test is a potential method in measuring moisture damage resistance in a laboratory. Results showed that the tensile strength ratios (TSR) of asphalt mixture with bagasse and coconut peat fillers are approximately equivalent to those with mineral fillers. Results also showed that asphalt mixtures with bagasse and coconut peat fillers can effectively prevent the moisture damage resistance. In addition, with the preliminary result, it was found that the POTS test showed a very good R square (R2) for a relation of TSR with the ITS test. As a result, the POTS can be a valid tool of quantifying moisture damage resistance with better simulating to field behavior, lower cost of equipment, and light weight.

This Special Issue “Recent Advances and Future Trends in Pavement Engineering” has been proposed and organized to present recent developments in the field of innovative pavement materials and engineering. For this reason, the articles and state-of-the-art reviews highlighted in this editorial relate to different aspects of pavement engineering, from recycled asphalt pavements to alkali-activated materials, from hot mix asphalt concrete to porous asphalt concrete, from interface bonding to modal analysis, from destructive testing to non-destructive pavement monitoring by using fiber optics sensors.

Moisture susceptibility is still one of the primary causes of distress in flexible pavements, reducing the pavements’ durability. A very large number of tests are available to evaluate the susceptibility of a binder aggregate combination. Tests can be conducted on the asphalt mixture, either in a loose or compacted form, or on the individual components of an asphalt pavement. Apart from various mechanisms and models, fundamental concepts have been proposed to calculate the thermodynamic tendency of a binder aggregate combination to adhere and/or debond under wet conditions. The aim of this review is to summarize literature findings and conclusions, regarding these concepts as carried out in the CEDR project FunDBits. The applied test methods, the obtained results, and the validation or predictability of these fundamental approaches are discussed.

The influence of compaction temperature on the mechanical resistance and susceptibility to water of a bound granular material with asphalt cement (called MGEA) was evaluated in laboratory. The above, because in temperate climates or low temperature, has been reported in some road projects, lowering the temperature of compaction with respect to the laboratory optimum to 30°C. Additionally, the technical construction specifications not recommend a range of compaction temperatures for the control of this material in road projects. This generates, that these materials are compacted empirically with temperatures that may not be appropriate. Two asphalt cements (AC 60-70 and AC 80-100) were used to prepare the MGEA mixtures. The compaction temperatures used were 105, 115, 125 and 135°C. Marshall, resilient modulus, permanent deformation and indirect traction tests were performed. The decrease of the compaction temperature produces a remarkable decrease in resistance under monotonic and cyclic loading, and increases moisture damage of the MGEA mixture tested.